Typically, routing of multicast IP traffic between domains occurs in two scenarios. A first scenario occurs when two wide area networks (e.g. ISPs) are connected to form a peer network. In this scenario, a gateway protocol (e.g. Multiprotocol Border Gateway Protocol) is used to negotiate dynamic routes (e.g. via PIM-SM) between the two autonomous networks. These networks are peers and imply a significant amount of trust between operators. Additionally, these networks require substantial information technology (IT) resources to successfully manage.
A second, and more common arrangement occurs when two networks having different domains are related in a Provider—User network domain relationship. An example is an Internet Service Provider (ISP)—Internet Service User (ISU) relationship. In this case, for multicasting to occur, this second arrangement simulates the behavior of a special host. For example, the user domain includes IP multicast clients which are adjacent to the provider's multicast router or are separated by multicast routers capable of proxying link-local multicast requests and thus are able to successfully request forwarding of desired multicast traffic. This second scenario could be considered a special case of inter-domain multicast dynamic routing.
This second scenario is frequently desirable because administration of each respective domain is self-contained and each domain expends resources to manage their own respective domain and users connected thereto. However, to implement dynamic multicast routing between domains is more complex, requiring significantly more effort. Additionally, dynamic multicast routing between domains requires two networked domains to be interconnected and exchanging information at a relatively high level. This results in substantial information technology security risks that administrators of both provider and user networks may be unwilling to manage.
At present, there is a lack of devices and/or protocols able to perform dynamic multicast routing, even via proxy. Further complicating matters, typical networks contain additional elements that can interfere with multicast routing such as firewalls which are common and frequently unable to handle dynamic routing protocols. Although some devices support proprietary functionality that overcomes some of these limitations, they tend to be ineffective in the common case of networks that are currently in existence using devices from multiple vendors.
Therefore, a need exists for a method and apparatus that enables multicast routing between domains where a peer relationship can be avoided and requires only limited IP multicast routing support on a user's network.
A system according to invention principles addresses these deficiencies and associated problems.